The woman in labor enters a tent, and the women of her tribe surround her and dance, and they encourage the birthing woman to dance with them, so as to make the birth less painful.
13 seconds sound clip from the Before Sunrise movie soundboard.
You can hear this line at 01:03:53 in the Blu-ray version of the movie.
Quote context
[...]
(small group applause in the street)
- Should I give her some money?
- Yeah.
- Everything that's interesting costs a little bit of money.
- So a birth dance, huh? Looked a little bit like a mating dance to me.
- No, but really, women used it when giving birth. In some part of the world, they still do it.
- And when the baby's born, they all dance in celebration.
- Wow. I don't think my mom would've gone for that.
- I like the idea of dancing as a common function in life, something everybody participates in.
[...]